Mobile communication is one of the most quickly developed and widely used communication fields. However, as the system coverage scope extends, the user number increases, and service providers provide diversified services, the networks become increasingly complicated. How to ensure security of the network and service information becomes an urgent issue to be solved.
After a relay node (RN) is introduced to the Long Term Evolution (LTE) system, the single-hop air interface link between the user equipment (UE) and the eNodeB (eNB) is segmented into an access link between the UE and the RN and a relay link between the RN and eNB. According to different modes of the security control, the security control may further classify into centralized security control and distributed security control.
Centralized security control indicates that a security association is directly established between the UE and eNB, but the intermediate node RN in the link does not participate in establishment of the security association. At the access network side, all key information related to the UE is stored and maintained only on the UE and eNB. No UE-related key information exists on the RN. Therefore, after the RN is introduced, no impact is made on the security mechanism (including identity authentication and key derivation processes) in the initial network entry process of the UE. The UE uses the traditional access authentication process of the LTE system for network access.
Distributed security control indicates that segments of security association are established between the UE and the RN and between the RN and the eNB respectively. The intermediate node RN in the link needs to save and maintain certain UE-related key information. Therefore, after the RN is introduced, a certain impact is made on the security mechanism in the initial network entry process of the UE. This impact exists in the derivation and distribution processes of the key.
To be compatible with the R8 UE, after the RN is introduced, the derivation hierarchy of the system key cannot be changed. That is, the eNB needs to continue to deliver the received shared key to the access site RN of the UE for the RN to further derive security keys used for the user plane and control plane based on the received shared key. In this way, the shared key between the UE and the eNB is the same as that between the UE and its access site RN so that the eNB can easily deduce or obtain the security keys used for the user plane and control plane in the access link between the UE and RN.
When developing the present invention, the inventor finds at least the following disadvantages of the prior art:
After the RN is introduced to the LTE system, huge hidden security risks exist in the segmented air interface link. The data transmitted through this air interface link is vulnerable to be attacked.